TMPRSS3 is a novel poor prognostic factor for breast cancer.

It has recently been reported that transmembrane protease, serine 3 (TMPRSS3) is overexpressed in cancer. However, TMPRSS3 expression and its biological roles in breast cancer (BC) have not been reported. This study aims to investigate the TMPRSS3 expression in BC and its relation with the outcome of the BC. This study involves a total of 149 BC tissues and adjacent non-cancerous tissues that were diagnosed between 2004 and 2007. Immunohistochemistry is used to compare the pattern of TMPRSS3 expression in BC and in adjacent non-cancerous tissues. Kaplan-Meier and Cox regression analyses were used to assess the prognostic significance of TMPRSS3 expression among BC patients. The results are as follow: TMPRSS3 expression is significantly in BC compared to adjacent non-cancerous tissues. High TMPRSS3 expression was related to TNM stage, lymph node metastasis, and Ki-67 expression. Furthermore, the overall survival (OS) and disease-free survival (DFS) in BC patients with high TMPRSS3 expression were lower than those in patients with low TMPRSS3 expression. Based on multivariate analysis, lymph node metastasis, TNM stage and TMPRSS3 expression are independent prognostic factors for OS in BC, while lymph node metastasis and TMPRSS3 expression are independent prognostic factors for DFS in BC. This study proves that TMPRSS3 expression is an independent prognostic factor for BC patients. Bioinformatic analysis of potential TMPRSS3 binding proteins revealed that TMPRSS3 could be a key regulator of cancer pathways. This study helps us better understand the function of TMPRSS3 in cancer.